In applications for cooktops, flame detection circuits using the current rectification method have been widely used for some time. With these known solutions, it is necessary at the stage of installing the cooktop to respect the polarity of the power outlet when wiring up the cooktop to the domestic power outlet, in order to guarantee the capacity for flame detection in all operating conditions of the control imposed by the market.
To this end, some constructors have recourse to or specify the use of transformers, in which one end of the secondary circuit is connected to the earth of the domestic network.
This solution is not, however, a low-cost solution, either in economic terms or in terms of space.
In the re-ignition devices currently on sale, the momentary absence of the flame, for example because of a gust of wind or liquids overflowing from a pan placed on the cooktop and momentarily interrupting a portion of the flame, leads immediately to the control producing sparks for reinstating the flame.
This behavior is in itself pointless from a functional point of view, since it is not necessary to reinstate a flame which is already present, and it is furthermore annoying for the user to hear the sparks being triggered, as well as causing wear on the sparkplugs which are pointlessly stressed.
In some re-ignition devices currently on sale, the momentary absence of the flame leads immediately to the device control producing sparks for reinstating the flame for a time determined by the hardware and not parametrizable. This timing is therefore not customizable according to the needs of the manufacturer of the cooktops, except by modifying the hardware.
Furthermore, these controls treat in the same way both conditions of first ignition and conditions where the flame has been disturbed, making the re-ignition device slow in conditions of first ignition.
Various re-ignition systems are furthermore known, such as the examples described in the following documents: U.S. Pat. Nos. 4,689,006, 5,439,374, 5,472,336, 6,985,080 B2, and U.S. Pat. No. 6,729,873 B2.
All these re-ignition systems, however, suffer from a series of disadvantages, like those indicated above.